flow like the river

BACK_BACK/node_modules/parcel-bundler/lib/utils/loadSourceMap.js

@@ -0,0 +1,86 @@
+"use strict";
+
+var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");
+
+var _asyncToGenerator2 = _interopRequireDefault(require("@babel/runtime/helpers/asyncToGenerator"));
+
+const logger = require('@parcel/logger');
+
+const path = require('path');
+
+const fs = require('@parcel/fs');
+
+const SOURCEMAP_RE = /(?:\/\*|\/\/)\s*[@#]\s*sourceMappingURL\s*=\s*([^\s*]+)(?:\s*\*\/)?/;
+const DATA_URL_RE = /^data:[^;]+(?:;charset=[^;]+)?;base64,(.*)/;
+
+function loadSourceMap(_x) {
+  return _loadSourceMap.apply(this, arguments);
+}
+
+function _loadSourceMap() {
+  _loadSourceMap = (0, _asyncToGenerator2.default)(function* (asset) {
+    // Get original sourcemap if there is any
+    let match = asset.contents.match(SOURCEMAP_RE);
+    let sourceMap;
+
+    if (match) {
+      asset.contents = asset.contents.replace(SOURCEMAP_RE, '');
+      let url = match[1];
+      let dataURLMatch = url.match(DATA_URL_RE);
+
+      try {
+        let json, filename;
+
+        if (dataURLMatch) {
+          filename = asset.name;
+          json = Buffer.from(dataURLMatch[1], 'base64').toString();
+        } else {
+          filename = path.join(path.dirname(asset.name), url);
+          json = yield fs.readFile(filename, 'utf8'); // Add as a dep so we watch the source map for changes.
+
+          asset.addDependency(filename, {
+            includedInParent: true
+          });
+        }
+
+        sourceMap = JSON.parse(json); // Attempt to read missing source contents
+
+        if (!sourceMap.sourcesContent) {
+          sourceMap.sourcesContent = [];
+        }
+
+        let missingSources = sourceMap.sources.slice(sourceMap.sourcesContent.length);
+
+        if (missingSources.length) {
+          let contents = yield Promise.all(missingSources.map( /*#__PURE__*/function () {
+            var _ref = (0, _asyncToGenerator2.default)(function* (source) {
+              try {
+                let sourceFile = path.join(path.dirname(filename), sourceMap.sourceRoot || '', source);
+                let result = yield fs.readFile(sourceFile, 'utf8');
+                asset.addDependency(sourceFile, {
+                  includedInParent: true
+                });
+                return result;
+              } catch (err) {
+                logger.warn(`Could not load source file "${source}" in source map of "${asset.relativeName}".`);
+              }
+            });
+
+            return function (_x2) {
+              return _ref.apply(this, arguments);
+            };
+          }()));
+          sourceMap.sourcesContent = sourceMap.sourcesContent.concat(contents);
+        }
+      } catch (e) {
+        logger.warn(`Could not load existing sourcemap of "${asset.relativeName}".`);
+        sourceMap = undefined;
+      }
+    }
+
+    return sourceMap;
+  });
+  return _loadSourceMap.apply(this, arguments);
+}
+
+module.exports = loadSourceMap;